Colorado rubberweed, olivaceous bitterweed

Actinella richardsonii (Hooker) Nuttall var. floribunda A. Gray, Mem. Amer. Acad. Arts, n. s. 4: 101. 1849

Plants 19–34 cm. Stems (2–)5–20(–30+), glabrous or ± hairy. Leaves glabrous or sparsely hairy. Heads (30–)80–250(–300+) per plant. Involucres 7–8 × 7–9 mm. Phyllaries: outer 8–9, strongly keeled, obovate, ovate, or lanceolate, 3.5–6 mm, apices acute; inner 8–12, 3–5 mm. Ray florets 7–9; corollas 7–11 mm. Disc florets 25–50+; corollas 3–4 mm. Cypselae 2 mm; pappi of (4–)5 obovate, aristate scales 1.8–2.8 mm. 2n = 30.

Flowering (May–)Jul–Aug(–Oct). Roadsides, open areas, edges of forests; (1600–)1800–2700(–3400) m; Ariz., Colo., N.Mex., Tex., Utah.